''Lacuna vincta'', commonly known as northern lacuna, wide lacuna, northern chink shell, or banded chink shell, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Littorinidae The Littorinidae are a taxonomic family of over 200 species of sea snails, marine gastropod molluscs in the clade Littorinimorpha, commonly known as periwinkles and found worldwide. Names In English-speaking countries, gastropod molluscs from ...

, the winkles or periwinkles. It is found intertidally and in shallow waters in both the northern Atlantic Ocean and the northern Pacific Ocean. It is a herbivore, feeding on

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

and

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

s with its toothed

radula The radula (; : radulae or radulas) is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters ...

Description

The shell of ''Lacuna vincta'' is conical, with five to six smooth whorls and a pointed apex. The aperture is about half the height of the shell or slightly larger. The umbilicus has a prominent groove between two white ridges of

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

. The exterior of the shell is pale brown with a broad spiral of white and a glossy

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods an ...

. The interior of the shell is not white and pearly and the aperture can be closed by an operculum. The maximum recorded

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

length is .Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". '' PLOS One'' 5(1): e8776. .

Distribution and habitat

The distribution of ''L. vincta'' is

circumboreal The Circumboreal Region in phytogeography is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan. It is the largest floristic region in ...

, extending as far south in the Atlantic Ocean as the British Isles and France, and the eastern coast of North America. In the northeastern Pacific its range extends from Alaska to California, but it is seldom found further south than Washington state. It is present on

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

on rocky shores, intertidally and down to about . In the British Isles, the larvae settle preferentially on brown seaweed such as ''

Fucus serratus ''Fucus serratus'' is a seaweed of the north Atlantic Ocean, known as toothed wrack, serrated wrack, or saw wrack. Description and reproduction ''Fucus serratus'' is a robust alga, olive-brown in colour and similar to ''Fucus vesiculosus'' an ...

'' and ''

Laminaria ''Laminaria'' is a genus of brown algae, brown seaweed in the order Kelp, Laminariales (kelp), comprising 31 species native to the north Atlantic and northern Pacific Oceans. This economically important genus is characterized by long, leathery L ...

'' spp. and on short red seaweed such as '' Lomentaria articulata'', as well as on the seagrass ''

Zostera ''Zostera'' is a small genus of widely distributed seagrasses, commonly called marine eelgrass, or simply seagrass or eelgrass. The genus ''Zostera'' contains 15 species. Ecology '' Zostera marina'' is found on sandy substrates or in estuarie ...

'' spp. In the Pacific they settle mainly on

kelp Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...

, eelgrass and surfgrass.

Ecology

''L. vincta'' is a

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

, grazing on

and on

s living on the surface of

seagrass Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...

es. The

has 45 to 95 rows of tiny teeth, with about three new rows being formed each day. Two separate types of teeth are produced; if the snail is grazing on seaweed, these newly formed teeth are sharply pointed and are used to tear deeply into the algal frond; if on the other hand, the snail is currently feeding on diatoms growing on seagrass, the new teeth are much blunter and are used to scrape diatoms off the leaves. The new teeth are formed at the back of the radula and work their way forward as the older teeth wear away and are discarded, so it takes some time for the snail's teeth to adjust to a change in diet. This snail favors sheltered positions and in exposed areas seeks the shelter of crevices or dense patches of seaweed. In unsuitable conditions, such as at times of food shortage or when there are excessive numbers of predators, it can produce a string of

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

which it uses as a "parachute" to help it to drift to a more favorable location. The sexes are separate in this snail with eggs being laid in a ring on seaweed or seagrasses. They may be laid throughout the year but in some locations, such as the British Isles, they are laid in the spring and early summer after which the adults die. The eggs hatch in about six days and the veliger larvae are

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

ic for up to six months before settling on the shallow seabed at a shell-length of about . In eastern Canada these juvenile snails have been recorded at a density of 1500 per square meter.

References

{{DEFAULTSORT:Lacuna Vincta Littorinidae Molluscs of the Atlantic Ocean Molluscs of the Pacific Ocean Gastropods described in 1803 Taxa named by George Montagu (naturalist)